Systems and methods for implementing hybrid automatic repeat request retransmission scheduling

ABSTRACT

A method of implementing a hybrid automatic repeat request (HARQ) process. The method includes: transmitting, by a transmitter to a receiver, an initial transmission of the HARQ process; receiving, by the transmitter from the receiver, receiver decoding capability information; setting, by the transmitter, a retransmission duration based on the receiver decoding capability information; and implementing, by the transmitter, a retransmission of the HARQ process based on the retransmission duration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and, under 35 U.S.C. § 119(e), claimspriority to U.S. Provisional Patent Application No. 62/900,288, filed onSep. 13, 2019 in the United States Patent and Trademark Office. Theentire contents of U.S. Provisional Patent Application No. 62/900,288are incorporated herein by reference.

FIELD

The present disclosure is generally related to wireless communicationsystems. In particular, the present disclosure is related to systems andmethods for implementing hybrid automatic repeat request (HARQ)retransmission (ReTx) scheduling.

BACKGROUND

HARQ is a retransmission scheme that can include one or more oftransmission by a transmitter to a receiver, feedback from the receiverto the transmitter, retransmission by the transmitter to the receiver,or combining of received signals (e.g., from an initial transmission anda retransmission) by the receiver.

SUMMARY

According to some embodiments, a method of implementing a HARQ process.The method includes: transmitting, by a transmitter to a receiver, aninitial transmission of the HARQ process; receiving, by the transmitterfrom the receiver, receiver decoding capability information; setting, bythe transmitter, a retransmission duration based on the receiverdecoding capability information; and implementing, by the transmitter, aretransmission of the HARQ process based on the retransmission duration.

According to some embodiments, a method of implementing a HARQ processincludes receiving, by a receiver from a transmitter, an initialtransmission of the HARQ process; transmitting, by the receiver to thetransmitter, receiver decoding capability information; receiving, by thereceiver from the transmitter, a retransmission; and implementing, bythe receiver, a decoding and feedback process for the retransmission.

According to some embodiments, a method of implementing a HARQ processincludes receiving, by a transmitter from a receiver, receiver decodingcapability information; receiving, by the transmitter from the receiver,feedback regarding a transmission of the HARQ process; and determining,by the transmitter, to implement a retransmission based on the feedback.The method further includes determining, by the transmitter, a decodingtime based on the receiver decoding capability information and based ona size of the retransmission; determining, by the transmitter based onthe decoding time, to implement a remediation process; and implementing,by the transmitter, the remediation process.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects, features, and advantages of certain embodiments of the presentdisclosure will be readily apparent from the following detaileddescription and the accompanying drawings.

FIG. 1 shows a diagram of a HARQ process including a retransmission,according to some embodiments.

FIG. 2 shows a diagram of improved HARQ processes that each include aretransmission, according to some embodiments.

FIG. 3 shows a diagram of a HARQ system including a transmitter and areceiver, according to some embodiments.

FIG. 4 shows a flowchart of a transmitter HARQ process that includesprocessing feedback for a HARQ retransmission, according to someembodiments.

FIG. 5 shows a flowchart of a receiver HARQ process that includes a HARQretransmission, according to some embodiments.

FIG. 6 shows a flowchart of a transmitter HARQ process that includes aremediation process, according to some embodiments.

FIG. 7 shows a diagram of an electronic device in a network environment,according to some embodiments.

DETAILED DESCRIPTION

Certain embodiments described herein involve a HARQ communicationscheme. HARQ retransmission and the combining of received signals canprovide for an increased probability that a receiver can decode areceived packet, which can improve accuracy and/or throughput. Certaincommunication systems, such as Wi-Fi systems, could benefit fromimplementing such a HARQ communication scheme. However, there arechallenges to implementing accurate, fast (e.g., high throughput), orefficient HARQ communication schemes in such communication systems.Certain embodiments described herein provide for improved HARQcommunication schemes, and may involve one or more improvedretransmission mechanisms or scheduling, feedback schemes, error codeschemes, remediation processes, and/or improved control signaling.

FIG. 1 shows a diagram of an example HARQ process that includes aretransmission. The depicted HARQ system 100 includes a transmitter 102and a receiver 104 performing a HARQ process. The transmitter 102 mayinclude one or more encoders configured to encode HARQ transmissions,and the receiver 104 may include one or more decoders configured todecode HARQ transmissions. For convenience, plural encoders or decoders(e.g., encoders or decoders configured to process data in parallel) maybe referred to herein simply as an encoder or a decoder (singular). Theexample HARQ process depicted in FIG. 1 involves an initial HARQtransmission (Tx), decoding, feedback, a retransmission (ReTx), andretransmission feedback.

As shown in FIG. 1, the transmitter 102 is configured to transmit, tothe receiver 104, a HARQ transmission comprising one or more physicallayer (“PHY”) data units (e.g., a physical layer convergence procedure(PLCP) protocol data unit (PPDU) that includes one or more HARQ units(physical layer units used in the HARQ process)) that include one ormore media access control (MAC) layer data units (e.g., MAC protocoldata units (MPDUs) or MAC service data units (MSDUs)). In the depictedexample, the initial HARQ transmission includes three HARQ units: HARQ1, HARQ 2, and HARQ 3. In other embodiments, a different number of HARQunits can be included in the HARQ transmission (e.g., one, two, four, ormore HARQ units).

The HARQ transmission that includes the three HARQ units is an “initial”transmission of the HARQ process (e.g., in that it is a firsttransmission of the HARQ process, possibly aside from certain initiationcommunications, certain handshake protocol communications, certainconnection establishing communications, or certain control informationcommunications). The HARQ transmission may be the first transmission inthe HARQ process that includes a data payload (e.g., a payload includingone or more MPDUs encoded in one or more HARQ units).

The receiver 104 may be configured to receive one or more HARQtransmissions and/or retransmissions from the transmitter 102, to decodethe one or more HARQ transmissions and/or retransmissions, and totransmit feedback information to the transmitter 102. In someembodiments, the receiver 104 is configured to decode HARQ units toextract MPDUs that were encoded in the HARQ units. In some embodiments,the receiver 104 is also or alternatively configured to process MPDUs(e.g., the MPDUs extracted from the HARQ units) to extract or analyzeinformation included in the MPDUs (such as MSDU information). In someembodiments, after decoding the HARQ units, the receiver 104 may beconfigured to extract the MPDUs, remove the MAC header(s) and extractthe MSDUs. Responsive to the MSDUs being correctly processed, thereceiver 104 may pass the MSDUs from the MAC layer to an upper layer.

The initial HARQ transmission may include control information (e.g., ina header (such as, for example, in a preamble of the header)), orcontrol information for the HARQ transmission may be sent out-of-band orindependently from the initial HARQ transmission, and the receiver 104may make use of such control information when decoding HARQ units orprocessing MPDUs included in the HARQ transmission.

The receiver 104 is configured to determine feedback information (whichmay be referred to herein as “feedback”) and to transmit the feedback tothe transmitter 102. The feedback may include acknowledgement (ACK) ornon-acknowledgement (NACK) information. The receiver 104 may determinethe feedback. For example, the receiver 104 may determine whether anerror is detected for at least some portion of the HARQ transmission,such that the at least some portion of the HARQ transmission is notcorrectly decoded or is not able to be (or is unlikely to be) correctlydecoded. The feedback may be used to cause the transmitter 102 to send aretransmission that may include, for example, the data that was notcorrectly decoded, or may include other information (e.g., parity bitsor other error management code, a different encoding of the initiallytransmitted data, or other data), and using this retransmission, thereceiver 104 may be able to decode the portion of the HARQ transmissionthat was not initially correctly decoded. Certain example techniques forusing the retransmission to decode the portion of the HARQ transmissionthat was not initially correctly decoded are described in detail below,including chase combining techniques and incremental redundancytechniques.

ACK information (which may be referred to herein as “ACK”) may indicatean acknowledgement that at least some of the information included in theHARQ transmission was correctly decoded and processed by the receiver104. The terms “correctly decoded” or “correctly processed,” as usedherein, can mean completely decoded or processed without errors, ordecoded or processed with an acceptable number of errors or anacceptable number of potential errors (such an acceptable number being,for example, predetermined (e.g., defined in a communication standard)),or can mean able to be (or sufficiently likely to be) decoded (e.g.,based on a determination performed by a receiver before decoding orprocessing is complete) without errors or decoded or processed with anacceptable number of errors, or an acceptable likelihood of a number oferrors being below a threshold, or an acceptable number of potentialerrors. “Potential errors” may be determined based on a determinedlikelihood of one or more errors.

The feedback may also, or alternatively, include NACK information (whichmay be referred to herein as “NACK”), which can indicate that at leastsome information included in the HARQ transmission was not correctlydecoded by the receiver 104. In some embodiments, when the receiver 104determines to send the NACK for at least a portion of the HARQtransmission, the receiver 104 does not send an ACK for other portionsof the HARQ transmission that were correctly decoded, and thetransmitter 102 is configured to interpret receipt of such a NACK as anindication that the portion of the HARQ transmission that the NACKpertains to was not correctly decoded, and, in some embodiments, also asan implicit indication that the other portion(s) of the HARQtransmission (the portion(s) of the HARQ transmission that the NACK doesnot pertain to) was correctly decoded. In some embodiments, the receiver104 may omit transmission of an ACK, and this omission may beinterpreted by the transmitter 102 as a NACK (e.g., responsive to thetransmitter 102 not receiving feedback from the receiver 104 within atime period designated for reception of feedback).

The transmitter 102 is configured to receive the feedback, and todetermine whether to send a retransmission to the receiver 104. As usedherein, the term “retransmission” can refer to a transmission subsequentto the initial transmission, or to a transmission responsive to feedbackreceived from the receiver 104. In some embodiments, the retransmissionhas a start time later than a start time of the initial transmission. Insome embodiments, the retransmission may partially temporally overlapwith the initial transmission. Although the retransmission shown in FIG.1 includes a single HARQ unit (“R unit 1”), in some embodiments, morethan one HARQ unit may be included in the retransmission.

The retransmission can include at least some of the same or similar dataincluded in the initial transmission, or information related to the dataincluded in the initial transmission (e.g., parity bits or other errormanagement code corresponding to the data included in the originaltransmission, or a different encoding of the initially transmitteddata). This data may include one or more HARQ units included in theinitial transmission, or one or more MPDUs included in the initialtransmission. The one or more HARQ units or MPDUs included in theinitial transmission may or may not be encoded differently thancorresponding HARQ units or MPDUs in the retransmission.

The transmitter 102 may use the retransmission at least in part toresend data that the feedback indicates was incorrectly decoded by thereceiver 104, or to send data related to data that was incorrectlydecoded by the receiver 104 (e.g., error code corresponding to the datathat was incorrectly decoded by the receiver 104). For example, if thetransmitter 102 receives a NACK indicating that a particular data unitwas not correctly decoded, the transmitter 102 may responsivelydetermine to send a retransmission that includes the particular dataunit, or error code corresponding to the particular data unit.

If the feedback indicates that all content of the HARQ transmission hasbeen correctly decoded and processed (e.g., if the feedback includes anACK indicating that all content of the HARQ transmission has beencorrectly decoded and processed), the transmitter 102 may responsivelydetermine to omit a retransmission. In some embodiments, the receiver104 sends current frame end (CF end) feedback, indicating that decodingand processing is complete, and responsive to receipt of the CF endfeedback the transmitter 102 may determine to omit a retransmission.

The receiver 104 may receive the retransmission, and may attempt todecode or process the data that was not initially correctly decoded orprocessed (e.g., that was not correctly decoded or processed on thebasis of the initial transmission). In some embodiments, the receiver104 may store data from the initial transmission that was not correctlydecoded or processed, and may use that data in combination with the dataincluded in the retransmission to correctly decode or process therelevant data. For example, the receiver 104 may implement a chasecombining technique. For chase combining, a retransmission may includethe same data and/or parity bits as included in the initialtransmission. The receiver 104 can use, for example, maximum-ratiocombining to combine the received bits with the corresponding bits fromthe initial transmission. As another example, the receiver 104 mayimplement an incremental redundancy technique. For incrementalredundancy, the retransmission includes different information than theinitial transmission. Multiple sets of parity bits may be generated,each based on the same set of information bits. The retransmission usesa different set of parity bits than the initial transmission, with adifferent redundancy version generated by the transmitter 102 bypuncturing an encoder output. Thus, with the retransmission, thereceiver gains extra information that can be used in conjunction withinformation received via the initial transmission.

Although a single retransmission is implemented in the embodiment shownin FIG. 1, multiple retransmissions may be implemented as part of theHARQ process. For example, the receiver 104 may transmit feedback to thetransmitter 102 responsive to one or more retransmissions (such feedbackmay be referred to here as “ReTx feedback”), and the transmitter 102 mayperform a retransmission responsive to the feedback (e.g., responsive toa ReTx NACK). When the transmitter 102 receives, from the receiver 104,an ACK that indicates (possibly in combination with previously receivedfeedback) that all data, or a sufficient amount of data, included in theinitial transmission has been correctly decoded or processed by thereceiver 104, the HARQ process may be concluded.

FIG. 1 shows certain scheduling challenges that may be encounteredduring the retransmission feedback process of the HARQ process 100.Referring first, for context, to the initial transmission feedbackprocess, which in the depicted example does not have any schedulingchallenges, the transmitter 102 may expect to receive feedback for theinitial transmission within a certain (e.g., predetermined) timeoutperiod after starting to send the initial transmission. The timeoutperiod may have a start point that coincides with a start point of theinitial transmitting. The timeout period may be based on a length of theinitial transmission (e.g., the timeout period may be determined by thetransmitter 102 to have a length equal to a length of the initialtransmission plus some additional time). Note that the term “length” asused herein may sometimes (but not necessarily always) be usedinterchangeably with the term “duration,” and it will be clear from thecontext when this is the case. The timeout period may end shortly afteran end point of the initial transmission (e.g., the additional time maybe equal to, or approximately equal to, one short interframe space(SIFS), or may be equal to some minimum timeframe permitted by therelevant communication scheme). The receiver 104 may begin processingthe initial transmission as it is received (e.g., the receiver 104 maybegin processing the HARQ 1 once it is received and before the HARQ 2and the HARQ 3 are fully received), which can help the receiver 104provide initial transmission feedback in a timely manner. In the exampledepicted in FIG. 1, the receiver 104 is able to process the initialtransmission and send feedback before an end of the initial transmissionfeedback timeout period.

However, in the example depicted in FIG. 1, the receiver does notprovide retransmission feedback in a timely manner. The transmitter 102may expect to receive feedback for the retransmission within a certain(e.g., predetermined) retransmission timeout period after starting tosend the retransmission. The timeout period may have a start point thatcoincides with a start point of the retransmission. The timeout periodmay be based on a length of the retransmission (e.g., the timeout periodmay be determined by the transmitter 102 to have a length equal to alength of the retransmission plus some additional time). Theretransmission feedback timeout period may end shortly after an endpoint of the retransmission (e.g., the additional time may be equal to,or approximately equal to, one short interframe space (SIFS)).

The retransmission may have a shorter length than the initialtransmission of the corresponding data unit (e.g., the depictedretransmission of HARQ 1 may be shorter than the initial transmission ofHARQ 1), for example, because less than the entire data unit may besent, or because error code (rather than the data unit itself) may besent as at least part of the retransmission. The length of the ReTxfeedback timeout period, which is based on the length of theretransmission, may correspondingly be shorter than the length of theinitial transmission feedback timeout period. Thus, the receiver 104 mayhave less time to provide feedback to the transmitter 102.

Furthermore, the receiver 104's processing of the retransmission maytake longer than the processing of the corresponding portion of theinitial transmission because, for example, the receiver 104 mayimplement a combining technique that makes use of both the initialtransmission data and retransmission data.

Thus, for the retransmission, the receiver 104 may have less time toprovide feedback to the transmitter 102 than for the initialtransmission, and/or the receiver 104 may use more time to process theretransmission than to process the initial transmission. One or more ofthese factors may lead to the scheduling challenges depicted in FIG. 1,and as shown in FIG. 1, the retransmission feedback timeout period endsbefore the receiver 104 is ready to provide feedback for theretransmission. This can be problematic, for example, because thetransmitter 102 may determine that no ACK has been received by the endof the retransmission feedback timeout period, and may interpret this asa NACK, possibly triggering the transmitter to incorrectly determinethat the transmission has failed and/or triggering an unnecessaryadditional retransmission to correct a perceived error.

FIG. 2 shows improved HARQ processes 200 a and 200 b. The HARQ processes200 a and 200 b are implemented using a transmitter 202 (which may besimilar to the transmitter 102 described above) and a receiver 204(which may be similar to the receiver 104 described above). In thedepicted HARQ process 200 a and the HARQ process 200 b, followingreceipt of the initial transmission, the receiver 204 sends bothfeedback and receiver decoding capability information (“Rx Cap”) to thetransmitter 202. The receiver decoding capability information caninclude information related to the receiver 204's decoding capability(e.g., an indication of the receiver's decoding throughput). Althoughthe Rx Cap is provided with the feedback in the depicted examples, asdiscussed in more detail below, the Rx Cap may be provided to thetransmitter in other ways.

In HARQ process 200 a, the transmitter 202 may set or adjust a durationof the retransmission based on the Rx Cap of the receiver 204. In thedepicted example, the duration of the retransmission is extendedrelative to the example shown in FIG. 1. Because a duration of theretransmission feedback timeout period is based on a duration of theretransmission (e.g., is equal to the duration of the retransmissionplus some additional time), the retransmission feedback timeout periodis also extended relative to the example shown in FIG. 1, and thereceiver 204 is able to provide retransmission feedback before an end ofthe retransmission feedback timeout period.

In the HARQ process 200 a, the transmitter 202 sets a target duration ofa retransmission of an “R unit 1” (a retransmission related to the HARQ1, which may include error code (e.g., parity bits) related to the HARQ1 and/or may include data included in the HARQ 1 (the data may possiblybe encoded differently than the encoding used for the HARQ 1)) such thatthe retransmission is longer than the retransmission shown in thecomparative example of FIG. 1. The transmitter 202 may use the Rx Cap tocalculate or estimate a decoding time (e.g., a likely decoding time, atarget decoding time, or a maximum decoding time) used by the receiver204 to process the retransmission (e.g., to decode the HARQ 1 using theretransmission), and may set a duration of the retransmission such thatthe retransmission feedback timeout period ends at or later than thecalculated or estimated decoding time. Thus the transmitter 202 may beconfigured to expect feedback regarding the retransmission at a moreappropriate time, which can decrease the chance that the transmitter 202will erroneously determine that the receiver 104 is not sending an ACKwhen in fact the receiver 204 is simply not yet done processing theretransmission.

In HARQ process 200 b, the transmitter 202 sets a duration of theretransmission feedback timeout period equal to the duration of theretransmission plus some additional time, and the transmitter 202 setsor adjusts a duration of the additional time based on the Rx Cap of thereceiver 204. The transmitter 202 may use the Rx Cap to calculate orestimate a decoding time (e.g., a likely decoding time, a targetdecoding time, or a maximum decoding time) used by the receiver 204 toprocess the retransmission (e.g., to decode the HARQ 1 using theretransmission), and may set a duration of the additional time such thatthe retransmission feedback timeout period ends at or later than thecalculated or estimated decoding time. Thus the transmitter 202 may beconfigured to expect feedback regarding the retransmission at a moreappropriate time, which can decrease the chance that the transmitter 202will erroneously determine that the receiver 204 is not sending an ACKwhen in fact the receiver 204 is simply not yet done processing theretransmission.

It is noted that in some embodiments, a retransmission feedback timeoutperiod may begin when the retransmission is complete. In suchembodiments, the retransmission feedback timeout period may correspondto, and be equal to, the “additional time” described herein.

It is noted that in some embodiments, one or more features of HARQprocess 200 a may be combined with one or more features of HARQ process200 b, as appropriate. In some embodiments, an adjusted transmissionduration (or setting of an appropriate transmission duration) may becombined with a process such as adjusting (or setting an appropriate)additional time. In some embodiments, a remediation process (e.g., asdescribed herein) may be implemented in combination with any of theabove techniques, as appropriate.

Referring now to FIG. 3, FIG. 3 shows a diagram of an improved HARQsystem 300 including the transmitter 202 and the receiver 204, accordingto some embodiments. The transmitter 202 and the receiver 204 may becommunication devices (e.g., any of a network device (e.g., a Wi-Fimodem or other networking device), or a client device (such as a laptop,mobile device, tablet, Internet of things (IoT) connected device, orother device)).

The components shown in FIG. 3 may be implemented as hardware, software,or a combination thereof. The components shown in FIG. 3 may beimplemented using one or more of the components shown in FIG. 7. Thetransmitter 202 may include a processor and memory storingprocessor-executable instructions for performing one or more processesdescribed herein. (e.g., as described below with respect to FIG. 7). Thereceiver 204 may include a processor and memory storingprocessor-executable instructions for performing one or more processesdescribed herein (e.g., as described below with respect to FIG. 7). Itis noted that although various components of the transmitter 202 and thereceiver 204 are described herein, by way of example, as beingconfigured to perform certain functions, those functions may beperformed by other components of the transmitter 202 and the receiver204, as appropriate.

The transmitter 202 includes an MPDU buffer 204, a HARQ transmissiongenerator 206, an interface (IF) 208, and a retransmission manager 210.In some embodiments, the HARQ transmission generator 206 retrieves MPDUsstored in the MPDU buffer 204, encodes the MPDUs into one or more HARQunits, and generates a HARQ transmission. The IF 208 sends the HARQtransmission to the receiver 204. In some embodiments, the IF 210receives feedback and/or Rx Cap information from the receiver 204 andsends the feedback and/or Rx Cap information to the retransmissionmanager 210. The retransmission manager may use the feedback and/or RxCap information to configure a retransmission in an improved manner asdescribed herein (e.g., using at least part of the HARQ process 200 aand/or at least a part of the HARQ process 200 b).

The MPDU buffer 204 is configured to store MPDUs and/or MSDUs. The MPDUsmay be MPDUs that are queued or temporarily stored by the transmitter202 for transmission to the receiver 204. The MPDUs may include MSDUsreceived from a logical link control (LLC) sublayer, and may include MACheader information. The MPDUs may have been encoded by the transmitter202, or may have been received by the transmitter 202 in encoded formfrom another device.

The HARQ transmission generator 206 is configured to generate HARQtransmissions using the MPDUs stored in the MPDU buffer 204. The HARQtransmission generator 206 may include an encoder configured to encodeone or more portions of a HARQ transmission. The HARQ transmission maybe any transmission of a HARQ process, including any of (but not limitedto) an initial transmission, a retransmission, or a connectionestablishing communication with another communication device (e.g., withthe receiver 204).

In some embodiments, the HARQ transmission generator 206 may configure aHARQ retransmission according to certain parameters, which can include,for example, parameters affecting a duration of the retransmission. Theparameters can include, for example, a modulation order, a number ofdata subcarriers N_(dsubc), and/or a number of retransmitted bitsN_(retran). The HARQ transmission generator 206 may also oralternatively configure the HARQ retransmission according to certainretransmission feedback timeout period parameters (e.g., aretransmission feedback timeout period duration or end point).

In some embodiments, the HARQ transmission generator 206 may beconfigured to set values for such parameters for a retransmission of aHARQ process based on information received from the retransmissionmanager 210. For example, the retransmission manager 210 may indicate tothe HARQ transmission generator 206 a decoding time for theretransmission, or a target retransmission duration, and theretransmission manager 210 may configure the retransmission accordingly.

In some embodiments, the HARQ transmission generator 206 may receivefrom the retransmission manager 210 an indication of Rx Cap informationof the receiver 204 (e.g., rather than receiving a decoding time for theretransmission, or a target retransmission duration). In suchembodiments, the HARQ transmission generator 206 may itself perform oneor more processes to determine the target retransmission duration (e.g.,processes described below as being performed by the retransmissionmanager 210, in certain other embodiments). The HARQ transmissiongenerator 206 may then configure the retransmission accordingly.

In some embodiments, the HARQ transmission generator 206 may receivefrom the retransmission manager 210 an indication of a decoding time forthe retransmission. The decoding time may be a time used by the receiver204 to decode the retransmission. This decoding time may be based on oneor more of the Rx Cap information, a size of the retransmission, or theretransmission scheme (e.g., chase combine or incremental redundancy).In some embodiments, the decoding time may be a minimum time used orneeded by the receiver 204 to decode the retransmission (e.g., may beequal to or similar to a data size of the retransmission divided by athroughput (as indicated in the Rx Cap information) of the receiver 204,as determined, for example, by the retransmission manager 210). Based onthe decoding time (and possibly based on determined additional time),the HARQ transmission generator 206 may determine a targetretransmission duration that provides sufficient time for the receiver204 to decode the retransmission and provide feedback by an end of theretransmission feedback timeout period. For example, assuming a certainadditional time (which may be determined by the HARQ transmissiongenerator 206 in any manner described herein (e.g., may be indicated bythe retransmission manager 210, or may be a default or predeterminedadditional time, such as 1 SIFS)), the HARQ transmission generator 206may select a target retransmission length such that the targetretransmission length in addition to the additional time is equal to, orgreater than, the decoding time. In some embodiments, the HARQtransmission generator 206 may select a target retransmission lengthsuch that the target retransmission length in addition to the additionaltime is equal to, or greater than, the decoding time in addition to atime used by the receiver 204 for determining and transmitting thefeedback for the retransmission.

In some embodiments, the HARQ transmission generator 206 may receivefrom the retransmission manager 210 an indication that a certainretransmission duration should be used or targeted (e.g., rather thanthe retransmission manager 210 providing a decoding time and the HARQtransmission generator 206 itself determining the retransmissionduration). The indication may include, for example, a specificretransmission duration, a minimum retransmission duration, a maximumretransmission duration, or a range of retransmission durations (e.g.,defined by a maximum and a minimum retransmission duration). Theindicated retransmission duration may be a target retransmissionduration, and the HARQ transmission generator 206 may set aretransmission duration that is closest to (and possibly at least aslarge as) the target retransmission duration, out of a set of candidateretransmission durations that are configurable or obtainable givencertain parameters the HARQ transmission generator 206 uses to set theretransmission duration.

The HARQ transmission generator 206 may set certain parameters for theretransmission to help achieve the target retransmission duration.Reference herein to setting a retransmission duration may refer tosetting parameters that affect the retransmission duration. Any of theabove parameters may be controlled or set by the HARQ transmissiongenerator 206 to help achieve the target retransmission duration, asappropriate. Generally speaking, the retransmission duration willincrease if N_(dsubc) decreases, and will increase if N_(retran)increases. In some embodiments, the HARQ transmission generator 206 mayperform processes to determine an adjustment from a default parametervalue or from a parameter value used for corresponding data of theinitial transmission, and may set the parameter value for theretransmission accordingly.

In some embodiments, the HARQ transmission generator 206 may set amodulation order for the retransmission based on (e.g., to help achieve)a target retransmission duration. For example, the HARQ transmissiongenerator 206 may set a low modulation order (e.g., lower than was usedfor the corresponding data of the initial transmission, or lower than adefault modulation order for retransmissions) for the retransmission,which corresponds to a long retransmission duration (e.g., longer thanthe transmission of the corresponding data in the initial transmission).The HARQ transmission generator 206 can determine the modulation order,for example, based on any of the target retransmission durationT_(target), N_(dsubc), or N_(retran).

By way of example, the following equation, or relationships betweenparameters defined by the equation, can be used to determine a targetnumber of bits per subcarrier N_(bps) for the retransmission:

$\begin{matrix}{N_{bps} = \frac{N_{retran}{Sym}\; {bolDuration}}{N_{dsubc}T_{target}}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

The following table shows correlations between the N_(bps) parameter andthe modulation order:

TABLE 1 N_(bps) Modulation order 1 Binary phase shift keying (BPSK) 2Quadrature phase shift keying (QPSK) 4 16 Quadrature amplitudemodulation (QAM) 6 64 QAM 8 256 QAM 10 1024 QAM . . . . . .The HARQ transmission generator 206 may determine a target N_(bps) basedon any of T_(target), N_(dsubc), or N_(retran) (e.g., using equation 1),and may use the target N_(bps) to set a modulation order for theretransmission accordingly (e.g., using a lookup table storing data thatindicates at least some of the correlations of table 1). The HARQtransmission generator 206 may use appropriate values for N_(dsubc)(e.g., an N_(dsubc) available for and/or allocated to theretransmission) and N_(retran) (e.g., an N_(retran) appropriate to theretransmission scheme being used and that accounts for the size of thedata that was not correctly processed by the receiver 204).

In some embodiments, the HARQ transmission generator 206 may determine atarget N_(dsubc) for the retransmission based on the targetretransmission duration (e.g., according to equation 1, using theindicated T_(target) and using appropriate values for N_(bps) andN_(retran)), and the HARQ transmission generator 206 may set N_(dsubc)for the retransmission based on the determined target N_(dsubc) (e.g.may set N_(dsubc) for the retransmission to the determined targetN_(dsubc) or may set N_(dsubc) for the retransmission to a closestpossible (given one or more other constraints), and possibly at least assmall as, N_(dsubc) to the target N_(dsubc)). Generally speaking (and ascan be seen in equation 1), the retransmission duration increases asN_(dsubc) decreases.

The HARQ transmission generator 206 may implement the target N_(dsubc)by allocating an appropriate resource unit (RU) size and/or anappropriate bandwidth (BW) for the retransmission. Generally speaking,allocating a smaller RU size results in a smaller N_(dsubc), andallocating a narrower bandwidth results in a smaller N_(dsubc).

In some embodiments, the HARQ transmission generator 206 may implement amultiuser (MU) or multiple-input-multiple-output (MIMO) scheme, in whichnumber of data subcarriers may be determined by, at least in part, thebandwidth (BW), or an RU size for orthogonal frequency-division multipleaccess (OFDMA) or MU cases. The HARQ transmission generator 206 mayconfigure the MU or MIMO scheme (e.g., by allocating the BW or the RUsize) such that the N_(dsubc) is set to, or is as close as possible to(e.g., given certain other constraints) the target N_(dsubc). In someembodiments, the HARQ transmission generator 206 may set the number ofdata subcarriers for the retransmission, at least in part, byappropriately aggregating multiple users in at least one multi-userphysical-layer-convergence-procedure protocol data unit (MU-PPDU) andallocating an appropriate resource unit (RU) size for each of themultiple users.

In some embodiments, the HARQ transmission generator 206 may configure anumber of special streams (e.g., in a single user case) such that theN_(dsubc) is set to, or is as close as possible to (e.g., given certainother constraints) the target N_(dsubc).

In some embodiments, the HARQ transmission generator 206 may determine atarget number of retransmitted bits N_(retran) for the retransmissionbased on the target retransmission duration (e.g., according to equation1, using the indicated T_(Target) and using appropriate values forN_(bps) and N_(dsubc)), and the HARQ transmission generator 206 may setN_(retran) for the retransmission based on the determined targetN_(retran) (e.g. may set N_(retran) for the retransmission to thedetermined target N_(retran), or may set N_(retran) for theretransmission to a closest possible (given one or more otherconstraints), and possibly at least as large as, N_(retran) to thetarget N_(retran)). Generally speaking (and as can be seen in equation1), the retransmission duration increases as N_(retran) increases.

In some embodiments, the HARQ transmission generator 206 may setN_(retran) at least in part by setting a certain number of parity bitsor information bits, by setting a number of incorrectly decoded dataunits addressed by the retransmission, or by including padding to theretransmission (e.g., dummy bits or placeholder bits).

Although some embodiments described herein involve the HARQ transmissiongenerator 206 setting only one parameter based on (e.g., to helpachieve) the target retransmission duration, in other embodiments, theHARQ transmission generator 206 may set a combination of any parametersdiscussed herein based on (e.g., to help achieve) the targetretransmission duration. For example, the HARQ transmission generator206 may set N_(retran) for the retransmission and at least one of (i) amodulation order for the retransmission or (ii) N_(dsubc) for theretransmission.

Thus, the HARQ transmission generator 206 may set a retransmissionduration that accommodates the Rx Cap (e.g., as shown in FIG. 2 for HARQprocess 200 a) by setting retransmission parameters, and the transmitter202 may thus be configured to expect feedback regarding theretransmission at an appropriate time, which can decrease the chancethat the transmitter 202 will erroneously determine that the receiver204 is not sending an ACK when in fact the receiver 204 is simply notyet done processing the retransmission.

Referring now to the IF 208, in some embodiments, the IF 208 is acommunication interface configured to transmit data from the transmitter202 to another device (e.g., to the receiver 204), and to receive datafrom another device (e.g., from the receiver 204). The IF 208 may beconfigured for one or more communication protocols, such as (but notlimited to) a Wi-Fi protocol or a local area network (LAN) protocol. TheIF 208 may be configured to process and transmit data, such as a HARQtransmission received from the HARQ transmission generator 206, to thereceiver 204. The IF 208 may be configured to receive data, such asfeedback or Rx Cap information, from the receiver 204. The IF 208 mayforward the feedback or Rx Cap information to the retransmission manager210.

The retransmission manager 210 may receive feedback information and RxCap information from the IF 208. The retransmission manager 210 mayprocess the feedback information and may instruct the HARQ transmissiongenerator 206 to implement a retransmission. The retransmission manager210 may process the Rx Cap information to provide to the HARQtransmission generator 206 an indication of any of the Rx Capinformation, a decoding time, a target retransmission duration, aretransmission feedback timeout period, an additional time for theretransmission feedback timeout period, or a remediation process. Theretransmission manager 210 may include a feedback manager 210 a and anRx Cap manager 210 b.

The feedback manager 210 a may process feedback from the receiver 204,including feedback regarding a retransmission of the HARQ process. Thefeedback manager 210 a may, in some embodiments, receive from the Rx Capmanager 210 b information regarding how feedback should be processed.For example, the feedback manager 210 a may receive from the Rx Capmanager 210 b an indication of a retransmission feedback timeout period,such as a length of the retransmission feedback timeout period, a startpoint of the retransmission feedback timeout period (e.g., based on aretransmission duration), and/or an end point of the retransmissionfeedback timeout period. The Rx Cap manager 210 b may, in someembodiments, indicate that the feedback manager 210 a should use defaultvalues for the retransmission feedback timeout period.

The feedback manager 210 a may, in some embodiments, receive from the RxCap manager 210 b an indication of a remediation process. The indicationmay, for example, be an indication regarding a delayed feedback scheme,and may specify an additional time for the retransmission feedbacktimeout period (e.g., and additional time longer than a defaultadditional time or longer than an additional time used in the initialtransmission), as shown, for example, in HARQ process 200 b. Theindication may, for example, be an indication regarding a deferredfeedback scheme, and may specify deferred feedback period after whichfeedback is “pulled” (e.g., after which the transmitter 202 sends arequest for the feedback to the receiver 204).

The feedback manager 210 a may process feedback regarding theretransmission using the information indicated by the Rx Cap manager 210b regarding the remediation process. For example, if the Rx Cap manager210 b indicates to the feedback manager 210 a to implement a delayedfeedback scheme with an extended additional time (e.g., a time longerthan 1 SIFS) for the retransmission feedback timeout period, thefeedback manager 210 a may responsively implement the extendedadditional time. If an ACK is received before the retransmissionfeedback timeout period expires, the feedback manager 210 a may end theHARQ process. If a NACK is received before the retransmission feedbacktimeout period, the feedback manager 210 a may, responsive to theretransmission feedback timeout period ending, instruct the HARQtransmission generator 206 to send another retransmission (e.g., inaccordance with a retransmission scheme, such as chase combine orincremental redundancy) or may determine to end the HARQ process (e.g.,if a time permitted for the HARQ process is insufficient to completeanother retransmission, or if a maximum number of retransmission hasalready been implemented). If no ACK is received before the end of theretransmission feedback timeout period, the feedback manager 210 a may,responsive to the retransmission feedback timeout period ending,instruct the HARQ transmission generator 206 to send anotherretransmission or to end the HARQ process (e.g., the feedback manager210 a may treat the lack of an ACK as a NACK).

The feedback manager 210 a may, in some embodiments, receive from the RxCap manager 210 b an indication that a deferred feedback scheme shouldbe implemented. The indication may include a deferred retransmissionfeedback timeout period, after which the transmitter 202 may pull thefeedback. In some embodiments, the initial transmission and theretransmission of the HARQ process may occur during a first TxOP, andthe feedback manager 210 a may, responsive to receiving from the Rx Capmanager 210 b the indication that a deferred feedback scheme should beimplemented, expect to receive the feedback following a pull of thefeedback by the transmitter 202, and/or may expect to receive thefeedback during a second TxOP different from the first TxOP (note thatalthough the terms “first” and “second” are used here, the first andsecond TxOPs need not be consecutive, and there may be one or more otherTxOPs between the first TxOP and the second TxOP). This can help toprovide sufficient time for the receiver 204 to decode theretransmission and provide feedback. The transmitter 202 may thus beconfigured to expect feedback regarding the retransmission at anappropriate time, which can decrease the chance that the transmitter 202will erroneously determine that the receiver 204 is not sending an ACKwhen in fact the receiver 204 is simply not yet done processing theretransmission. The deferred feedback scheme may, in some embodiments,be implemented in combination with any other technique described herein,as appropriate.

Referring now to the Rx Cap manager 210 b, in some embodiments, the RxCap manager 210 b may set a target retransmission duration based on theRx Cap information. In some embodiments, the Rx Cap manager maydetermine, based on the Rx Cap information, that a remediation process(e.g., a delayed feedback schedule and/or a deferred feedback scheme)should be implemented. In some embodiments, the Rx Cap manager 210 bdetermines that the remediation process should be implemented responsiveto determining, based on the Rx Cap information, that the receiver doesnot have sufficient decoding capabilities to process the retransmissionwithout implementation of a remediation process.

In some embodiments, the Rx Cap manager 210 b sets a targetretransmission duration based on the Rx Cap information, and indicatesthe target retransmission duration to the HARQ transmission generator206. The Rx Cap information may indicate a decoding throughput of thereceiver 204. The Rx Cap manager 210 b may determine a decoding time(e.g., a likely decoding time, a target decoding time, or a maximumdecoding time) used by the receiver 204 to process the retransmission,and may set a target duration of the retransmission such that aretransmission feedback timeout period, which is based on theretransmission duration, ends at or later than the calculated orestimated decoding time. In making this determination, the Rx Capmanager 210 b may make use of an estimated retransmission feedbacktimeout period (e.g., a default retransmission feedback timeout periodor a retransmission feedback timeout period determined in any mannerdescribed herein, as appropriate).

In some embodiments, the Rx Cap manager 210 b determines that aremediation process should be implemented responsive to determining,based on the Rx Cap information, that the receiver does not havesufficient decoding capabilities to process the retransmission withoutimplementation of a remediation process. The Rx Cap manager 210 b maymake this determination based on any of a throughput of the receiver 204included in the Rx Cap information, a size of the retransmission, aretransmission length or end point of the retransmission, aretransmission scheme, and a default or estimated retransmissionfeedback timeout period. For example, the Rx Cap manager 210 b maydetermine a decoding time based on at least the size of thetransmission, the retransmission scheme, and a decoder throughputincluded in the Rx Cap information, and may determine that the defaultor estimated retransmission feedback timeout period length isinsufficient to encompass an estimated time at which the transmitter 202should receive feedback (based on the decoding time, and possibly basedon time for transmitting the feedback (e.g., propagation time)). In someembodiments, the Rx Cap manager 210 b may determine that implementing amaximum possible (given certain constraints or requirements)retransmission length would still result in the default or estimatedretransmission feedback timeout period being insufficient to encompassan estimated time at which the receiver 202 expects to receive feedback,and the Rx Cap manager 210 b may then responsively determine toimplement the remediation process.

Responsive to determining that the receiver does not have sufficientdecoding capabilities to process the retransmission withoutimplementation of a remediation process, the Rx Cap manager 210 b may,in some embodiments, transmit to the feedback manager 210 a anindication of a remediation process. The indication may, for example, bean indication regarding a delayed feedback scheme, and may specify anextended additional time for the retransmission feedback timeout periodlonger than a default additional time for the retransmission feedbacktimeout period (e.g., longer than 1 SIFS). The indication may, forexample, be an indication regarding a deferred feedback scheme, and mayspecify a deferred feedback scheme timeout period after which thetransmitter 202 pulls feedback from the receiver 204.

In some embodiments, the Rx Cap manager 210 b may determine, based onthe Rx Cap information, an appropriate additional time for theretransmission feedback timeout period. The Rx Cap manager 210 b may setor adjust a length of the additional time for the retransmissionfeedback timeout period based on an estimated decoding time (e.g., alikely decoding time, a target decoding time, or a maximum decodingtime) used by the receiver 204 to process the retransmission, and mayset a duration of the additional time for the retransmission feedbacktimeout period such that the retransmission feedback timeout period endsat or later than the an expected time by which the receiver 204 willprovide feedback for the retransmission. The Rx Cap manager 210 b maymake use of a retransmission duration (this information may be indicatedby the HARQ transmission generator 206 to the Rx Cap manager 210 b) indetermining the appropriate length of the additional time for theretransmission feedback timeout period. For example, the Rx Cap manager210 b may determine that the additional time for the retransmissionfeedback timeout period should be equal to or larger than an amount bywhich the decoding time exceeds the retransmission length, or that theadditional time for the retransmission feedback timeout period should beequal to or larger than an amount by which (the decoding time plus atime for transmitting feedback (e.g., 1 SIFS)) exceeds theretransmission length. The Rx Cap manager 210 b may indicate to thefeedback manager 210 a the determined additional time for theretransmission feedback timeout period or the retransmission feedbacktimeout period itself (which is based on the determined additional timefor the retransmission feedback timeout period), or any of a length ofthe retransmission feedback timeout period, a start point of theretransmission feedback timeout period (e.g., based on a retransmissionduration), and/or an end point of the retransmission feedback timeoutperiod.

As discussed above, by using the Rx Cap manager 210 b to appropriatelyset the retransmission feedback timeout period based on the Rx Cap(e.g., to a length longer than a default length or to a length longerthan the length of the retransmission feedback timeout periodcorresponding to the initial transmission of the HARQ process), theretransmission manager 210 can help avoid erroneously determine that thereceiver 104 is not sending an ACK when in fact the receiver 204 issimply not yet done processing the retransmission.

Referring now to the receiver 204, the receiver 204 may include an IF212, a HARQ transmission manager 214, and a data storage 216. The HARQtransmission manager 214 may process data received from the transmitter202 as part of a HARQ process, and may indicate to the transmitter 202(via the IF 212) Rx Cap information.

In some embodiments, the IF 212 may include a communication interfaceconfigured to transmit data from the receiver 204 to another device(e.g., to the transmitter 202), and to receive data from another device(e.g., from the transmitter 202). The IF 212 may be configured for oneor more communication protocols, such as (but not limited to) a Wi-Fiprotocol or a local area network (LAN) protocol. The IF 212 may beconfigured to process and receive data, such as a HARQ transmission,from the transmitter 202. The IF 212 may be configured to transmit data,such as feedback for the HARQ process, to the transmitter 202. The IF212 may receive such feedback from the HARQ transmission manager 214.The IF 212 may forward a received HARQ transmission to the HARQtransmission manager 214.

In some embodiments, the HARQ transmission manager 214 includes adecoder 214 a and a feedback manager 214 b. The decoder 214 a mayinclude one or a plurality of decoders (e.g., that may be configured todecode in parallel), but is referred to herein in the singular forsimplicity. The decoder 214 a may be configured to decode the physicallayer units included in a HARQ transmission to extract MPDUs, and may beconfigured to process the MPDUs (e.g., to extract MSDUs). The decoder214 a may make use of control information received from the transmitter202 to decode the HARQ transmission. The decoder 214 a may use of errordetecting code (e.g., cyclic redundancy check (CRC) code) included inthe HARQ transmission being processed to detect errors, or to confirm noerrors, in the HARQ transmission.

In some embodiments, the feedback manager 214 b determines feedback forthe HARQ transmission and indicates to the transmitter 202 Rx Capinformation. The feedback manager 214 b may include a feedback generator214 c and a decoder capabilities indicator 214 d.

In some embodiments, the feedback generator 214 c may generate feedbackregarding the decoding and processing of the HARQ transmission decodedand processed by the decoder 214 a, and may send the feedback to the IF212 for transmission to the transmitter 202. For example, the decoder214 a may indicate to the feedback generator 214 c that one or more dataunits of the HARQ transmission were correctly decoded or processed, andthe feedback generator 214 c may responsively generate an ACK indicatingthis, and may send the ACK to the transmitter 202 via the IF 212.

By way of further example, the decoder 214 a may indicate to thefeedback generator 214 c that a data unit includes a detected error(e.g., detected using CRC code included in the HARQ transmission). Thefeedback generator 214 c may responsively generate NACK feedbackindicating this, and may send the NACK to the transmitter 202 via the IF212.

In some embodiments, the feedback generator 214 c may store one or moredata units that were not correctly decoded or processed in the datastorage 216 and/or related data (e.g., error code corresponding to datathat was not correctly decoded or processed, such as parity bits) asdata for combining 216 a. The data for combining 216 a may be used bythe HARQ transmission manager 214 in conjunction with one or more dataunits received in a retransmission of the HARQ process to correctlydecode or process a data unit of interest. For example, the HARQtransmission manager 214 may implement a chase combining technique or anincremental redundancy technique that makes use of the data forcombining 216 a and one or more data units received in theretransmission.

In some embodiments, the feedback generator 214 c may receive, via theIF 212, an indication to implement a deferred feedback scheme. Thefeedback generator 214 c may implement a feedback process accordingly(e.g., may wait for a pull request from the transmitter 202 to send thedeferred feedback).

In some embodiments, the decoder capabilities indicator 214 d mayindicate to the transmitter 202 Rx Cap information including, forexample, a throughput of the decoder 214 a. The Rx Cap information maybe stored in data storage 216. In some embodiments, the Rx Capinformation may be predetermined (e.g., at a time of initial calibrationof the receiver 204, or included in firmware of the receiver 204, orpreprogrammed at a time of manufacture of the receiver 204). In someembodiments, the Rx Cap information may be determined (e.g.,dynamically) by the decoder capabilities indicator 214 d based oncalibration, monitoring, or testing of the decoder 214 a's decodingcapabilities.

The decoder capabilities indicator 214 d may indicate the Rx Capinformation to the transmitter 202 via the IF 212. The decodercapabilities indicator 214 d may indicate the Rx Cap information to thetransmitter 202 as part of the feedback regarding a transmission of theHARQ process (e.g., as part of a feedback frame), as part of acapabilities exchange (e.g., a process of the receiver 204 indicatingHARQ capability), as part of a control frame for the HARQ process, or aspart of a connection establishing procedure (e.g., an associationprocedure, wherein an association between transmitter 202 and thereceiver 204 is established, such as when transmitter 202 tries tocreate a link with the receiver 204).

In some embodiments, the decoder capabilities indicator 214 d mayindicate the Rx Cap information to the transmitter 202 as part of arequest to adjust a retransmission duration or to implement aremediation process. The feedback manager 214 b may determine to send arequest to adjust a retransmission duration or to implement aremediation process based on determining that an estimated or defaultretransmission feedback timeout period is insufficient to encompass anestimated time at which the transmitter 202 should receive feedback(based on the decoding time, and possibly based on time for transmittingthe feedback). In some embodiments, the feedback manager 214 b maydetermine that the estimated or default retransmission feedback timeoutperiod is insufficient to encompass the estimated time at which thereceiver 202 should receive feedback in any manner described herein(e.g., as described with respect to the Rx Cap manager 210 b).

Referring now to FIG. 4, FIG. 4 shows a flow of a HARQ process 400. TheHARQ process 400 includes transmitting an initial transmission of a HARQprocess (402), receiving receiver decoding capability information (404),setting a retransmission duration based on the receiver decodingcapability information (406), and implementing a retransmission of theHARQ process based on the retransmission duration (408).

In some embodiments, in operation 402, the transmitter 202 may transmitan initial transmission of a HARQ process 400 to the receiver 204. Theinitial transmission may include a data payload for the HARQ process400. The initial transmission may be subsequent to a connectionestablishing process.

In some embodiments, in operation 404, the transmitter 202 may receiveRx Cap information from the receiver 204. The Rx Cap information mayindicate a decoding throughput of the receiver 204. The transmitter 202may receive the Rx Cap information as part of feedback regarding theinitial transmission of the HARQ process 400 (e.g., as part of afeedback frame), as part of a capabilities exchange (e.g., a process ofthe receiver 204 indicating HARQ capability), as part of a control framefor the HARQ process 400, or as part of a connection establishingprocedure (e.g., an association procedure, wherein an associationbetween transmitter 202 and the receiver 204 is established, such aswhen transmitter 202 tries to create a link with the receiver 204).

In some embodiments, in operation 406, the transmitter 202 may set aretransmission duration based on the receiver decoding capabilityinformation, and may indicate the retransmission duration to the HARQtransmission generator 206. For example, the Rx Cap manager 210 b maydetermine a decoding time (e.g., a likely decoding time, a targetdecoding time, or a maximum decoding time) used by the receiver 204 toprocess the retransmission based on the Rx Cap information, and may seta target duration of the retransmission such that a retransmissionfeedback timeout period ends at or later than the calculated orestimated decoding time. In making this determination, the Rx Capmanager 210 b may make use of an estimated retransmission feedbacktimeout period (e.g., a default retransmission feedback timeout periodor a retransmission feedback timeout period determined in any mannerdescribed herein, as appropriate). The HARQ transmission generator 206may set the retransmission duration to the indicated retransmissionduration by setting one or more retransmission parameters. Theparameters can include, for example, a modulation order, a number ofdata subcarriers N_(dsubc), a number of retransmitted bits N_(retran).These parameters may be set or determined in any appropriate mannerdescribed herein (e.g., as described in reference to the HARQtransmission generator 206).

In some embodiments, in operation 408, the transmitter 202 may implementa retransmission of the HARQ process 400 based on the retransmissionduration. The retransmission may be implemented used the retransmissionparameters set in operation 406.

Thus, the transmitter 202 may configure a retransmission thataccommodates the Rx Cap, and the transmitter 202 may thus be configuredto expect feedback regarding the retransmission at an appropriate time,which can decrease the chance that the transmitter 202 will erroneouslydetermine that the receiver 204 is not sending an ACK when in fact thereceiver 204 is simply not yet done processing the retransmission.

Referring now to FIG. 5, FIG. 5 shows a flow of a HARQ process 500. TheHARQ process 500 includes receiving an initial transmission of the HARQprocess 500 (502), transmitting receiver decoding capability information(504), receiving a retransmission (506), and implementing a decoding andfeedback process for the retransmission (508).

In some embodiments, in operation 502, the receiver 204 may receive aninitial transmission of the HARQ process 500. The initial transmissionmay include a data payload for the HARQ process 500. The initialtransmission may be subsequent to a connection establishing process.

In some embodiments, in operation 504, the receiver 204 may transmit RxCap information to the transmitter 202. The Rx Cap information mayindicate a decoding throughput of the receiver 204. The Rx Capinformation may be stored in data storage 216. In some embodiments, theRx Cap information may be predetermined (e.g., at a time of initialcalibration of the receiver 204, or included in firmware of the receiver204, or preprogrammed at a time of manufacture of the receiver 204). Insome embodiments, the Rx Cap information may be determined by thedecoder capabilities indicator 214 d based on calibration, monitoring,or testing of the decoder 214 a's decoding capabilities.

In some embodiments, in operation 506, the receiver 204 may receive aretransmission duration from the transmitter 202, and in operation 508,the receiver 204 may implement a decoding and feedback process for theretransmission. In some embodiments the decoder 214 a may process anddecode the retransmission (e.g., using a chase combining technique usingthe data for combining 216 a stored in the receiver 204's data storage216, or using an incremental redundancy technique). In some embodiments,the feedback generator 214 c may provide feedback for the retransmissionto the transmitter 204 via the IF 212.

The receiver's transmission of Rx Cap information may allow thetransmitter 202 to set a retransmission duration or other retransmissionparameters that accommodates the Rx Cap information, and the transmitter202 may thus be expect feedback regarding the receiver 204'sretransmission at an appropriate time, which can decrease the chancethat the transmitter 202 will erroneously determine that the receiver204 is not sending an ACK when in fact the receiver 204 is simply notyet done processing the retransmission.

Referring now to FIG. 6, FIG. 6 shows a flow of a HARQ process 600. TheHARQ process 600 includes receiving receiver decoding capabilityinformation (602), receiving feedback regarding a transmission of theHARQ process 600 (604), determining to implement a retransmission basedon the feedback (606), determining a decoding time based on the receiverdecoding capability information and based on a size of theretransmission (608), determining, based on the decoding time, toimplement a remediation process (610), and implementing the remediationprocess (612).

In some embodiments, in operation 602, the transmitter 202 may receiveRx Cap of the receiver 204. The Rx Cap information may indicate adecoding throughput of the receiver 204.

In some embodiments, in operation 604, the transmitter 202 may receiveNACK feedback regarding a transmission of the HARQ process 600 (e.g., aninitial transmission or a retransmission of the HARQ process 600)indicating that one or more data units of the transmission of the HARQprocess 600 were not correctly decoded or processed.

In some embodiments, in operation 606, the transmitter 202 may determineto implement a retransmission based on the NACK feedback. Thetransmitter 202 may make this determination responsive to determiningthat a timeout period for the overall HARQ process 600 or for the HARQprocess 600 has not yet been reached or exceeded.

In some embodiments, in operation 608, the transmitter 202 may determinea decoding time (e.g., a likely decoding time, a target decoding time,or a maximum decoding time) used by the receiver 204 to process theretransmission, based on the receiver decoding capability informationand based on a size of the retransmission. In some embodiments, thedecoding time may be a minimum or likely time used or needed by thereceiver 204 to decode the retransmission (e.g., may have a durationequal to or similar to a size of the retransmission divided by athroughput (as indicated in the Rx Cap information) of the receiver 204,as determined, for example, by the retransmission manager 210).

In some embodiments, in operation 610, the transmitter 202 maydetermine, based on the decoding time, to implement a remediationprocess. In some embodiments, the Rx Cap manager 210 b of thetransmitter 202 may determine that the default or estimatedretransmission feedback timeout period is insufficient to encompass anestimated time at which the transmitter 202 should receive feedback(based on the decoding time, and possibly based on time for transmittingthe feedback), and in some embodiments the Rx Cap manager 210 b mayresponsively determine to implement a remediation process. In someembodiments, the Rx Cap manager 210 b may determine that implementing amaximum possible (given certain constraints or requirements)retransmission length would still result in the default or estimatedretransmission feedback timeout period being insufficient to encompassan estimated time at which the receiver 202 should receive feedback, andthe Rx Cap manager 210 b may then responsively determine to implementthe remediation process.

In some embodiments, in operation 612, the transmitter 202 may implementthe remediation process. The remediation process may include a delayedfeedback scheme or a deferred feedback scheme in any appropriate mannerdescribed here.

Thus, the transmitter 202 may configure a retransmission thataccommodates the Rx Cap, and the transmitter 202 may thus be configuredto expect feedback regarding the retransmission at an appropriate time,which can decrease the chance that the transmitter 202 will erroneouslydetermine that the receiver 204 is not sending an ACK when in fact thereceiver 204 is simply not yet done processing the retransmission.

FIG. 7 shows a diagram of an electronic device 701 in a networkenvironment 700, according to some embodiments. Referring to FIG. 7, theelectronic device 701 in the network environment 700 may communicatewith an electronic device 702 via a first network 798 (e.g., ashort-range wireless communication network, such as a Wi-Fi network), oran electronic device 704 or a server 708 via a second network 799 (e.g.,a long-range wireless communication network). The electronic device 701may communicate with the electronic device 704 via the server 708. Theelectronic device 701 may include a processor 720, a memory 730, aninput device 750, a sound output device 755, a display device 760, anaudio module 770, a sensor module 776, an interface 777, a haptic module779, a camera module 780, a power management module 788, a battery 789,a communication module 790, a subscriber identification module (SIM)796, and/or an antenna module 797. In one embodiment, at least one ofthe components (e.g., the display device 760 or the camera module 780)may be omitted from the electronic device 701, or one or more othercomponents may be added to the electronic device 701. In one embodiment,some of the components may be implemented as a single integrated circuit(IC). For example, the sensor module 776 (e.g., a fingerprint sensor, aniris sensor, or an illuminance sensor) may be embedded in the displaydevice 760 (e.g., a display), or the display device 760 may include oneor more sensors in addition to the sensor module 776.

In some embodiments, the device 701 may include the transmitter 202, andone of the devices 702, 704, or 708 may be, or a device managing thenetwork 798 or the network 799 may include, the receiver 204. In someembodiments, the device 701 may include the receiver 204, and one of thedevices 702, 704, or 708 may be, or a device managing the network 798 orthe network 799 may include, the transmitter 202. In some embodiments,the HARQ system 100 includes a first device 701 and a second device 701,the transmitter 202 is included in the first device 701, and thereceiver 204 is included in the second device 701.

The processor 720 may execute, for example, software (e.g., a program740) to control at least one other component (e.g., a hardware or asoftware component) of the electronic device 701 coupled with theprocessor 720, and may perform various data processing and/orcomputations. As at least a part of the data processing and/orcomputations, the processor 720 may load a command or data received fromanother component (e.g., the sensor module 776 or the communicationmodule 790) in volatile memory 732, process the command or the datastored in the volatile memory 732, and store resulting data innon-volatile memory 734. The processor 720 may include a main processor721 (e.g., a central processing unit (CPU) or an application processor(AP)), and an auxiliary processor 723 (e.g., a graphics processing unit(GPU), an image signal processor (ISP), a sensor hub processor, or acommunication processor (CP)) that is operable independently from, or inconjunction with, the main processor 721. Additionally or alternatively,the auxiliary processor 723 may be adapted to consume less power thanthe main processor 721, and/or execute a particular function. Theauxiliary processor 723 may be implemented as being separate from, or asa part of, the main processor 721.

The auxiliary processor 723 may control at least some of the functionsor states related to at least one component (e.g., the display device760, the sensor module 776, or the communication module 790) from amongthe components of the electronic device 701, instead of the mainprocessor 721 while the main processor 721 is in an inactive (e.g.,sleep) state, or together with the main processor 721 while the mainprocessor 721 is in an active state (e.g., executing an application).According to one embodiment, the auxiliary processor 723 (e.g., an imagesignal processor or a communication processor) may be implemented as apart of another component (e.g., the camera module 780 or thecommunication module 790) functionally related to the auxiliaryprocessor 723.

The memory 730 may store various data used by at least one component(e.g., the processor 720 or the sensor module 776) of the electronicdevice 701. The various data may include, for example, software (e.g.,the program 740) and input data or output data for a command relatedthereto. The memory 730 may include the volatile memory 732 and/or thenon-volatile memory 734.

The program 740 may be stored in the memory 730 as software, and mayinclude, for example, an operating system (OS) 742, middleware 744, oran application 746.

The input device 750 may receive a command or data to be used by anothercomponent (e.g., the processor 720) of the electronic device 701, fromthe outside (e.g., a user) of the electronic device 701. The inputdevice 750 may include, for example, a microphone, a mouse, and/or akeyboard.

The sound output device 755 may output sound signals to the outside ofthe electronic device 701. The sound output device 755 may include, forexample, a speaker or a receiver. The speaker may be used for generalpurposes, such as playing multimedia or recording, and the receiver maybe used for receiving an incoming call. According to one embodiment, thereceiver may be implemented as being separate from, or as a part of, thespeaker.

The display device 760 may visually provide information to the outside(e.g., a user) of the electronic device 701. The display device 760 mayinclude, for example, a display, a hologram device, and/or a projectorand control circuitry to control a corresponding one of the display, thehologram device, and the projector. According to one embodiment, thedisplay device 760 may include touch circuitry adapted to detect atouch, or sensor circuitry (e.g., a pressure sensor) adapted to measurethe intensity of force incurred by the touch.

The audio module 770 may convert a sound into an electrical signal andvice versa. According to one embodiment, the audio module 770 may obtainthe sound via the input device 750, and/or output the sound via thesound output device 755 or a headphone of an external electronic device702 directly (e.g., wired) or wirelessly coupled with the electronicdevice 701.

The sensor module 776 may detect an operational state (e.g., power ortemperature) of the electronic device 701 and/or an environmental state(e.g., a state of a user) external to the electronic device 701, andthen generate an electrical signal or data value corresponding to thedetected state. The sensor module 776 may include, for example, agesture sensor, a gyro sensor, an atmospheric pressure sensor, amagnetic sensor, an acceleration sensor, a grip sensor, a proximitysensor, a color sensor, an infrared (IR) sensor, a biometric sensor, atemperature sensor, a humidity sensor, and/or an illuminance sensor.

The interface 777 may support one or more specified protocols to be usedfor the electronic device 701 to be coupled with the external electronicdevice 702 directly (e.g., wired) or wirelessly. According to oneembodiment, the interface 777 may include, for example, a highdefinition multimedia interface (HDMI), a universal serial bus (USB)interface, a secure digital (SD) card interface, and/or an audiointerface.

A connecting terminal 778 may include a connector via which theelectronic device 701 may be physically connected with the externalelectronic device 702. According to one embodiment, the connectingterminal 778 may include, for example, an HDMI connector, a USBconnector, an SD card connector, and/or an audio connector (e.g., aheadphone connector).

The haptic module 779 may convert an electrical signal into a mechanicalstimulus (e.g., a vibration or a movement) and/or an electrical stimuluswhich may be recognized by a user via tactile sensation or kinestheticsensation. According to one embodiment, the haptic module 779 mayinclude, for example, a motor, a piezoelectric element, and/or anelectrical stimulator.

The camera module 780 may capture a still image or moving images.According to one embodiment, the camera module 780 may include one ormore lenses, image sensors, image signal processors, and/or flashes.

The power management module 788 may manage power supplied to theelectronic device 701. The power management module 788 may beimplemented as at least a part of, for example, a power managementintegrated circuit (PMIC).

The battery 789 may supply power to at least one component of theelectronic device 701. According to one embodiment, the battery 789 mayinclude, for example, a primary cell which is not rechargeable, asecondary cell which is rechargeable, and/or a fuel cell.

The communication module 790 may support establishing a direct (e.g.,wired) communication channel or a wireless communication channel betweenthe electronic device 701 and the external electronic device (e.g., theelectronic device 702, the electronic device 704, and/or the server 708)and performing communication via the established communication channel.The communication module 790 may include one or more communicationprocessors that are operable independently from the processor 720 (e.g.,the AP) and may support a direct (e.g., wired) communication and/or awireless communication. According to one embodiment, the communicationmodule 790 may include a wireless communication module 792 (e.g., acellular communication module, a short-range wireless communicationmodule, and/or a global navigation satellite system (GNSS) communicationmodule) or a wired communication module 794 (e.g., a local area network(LAN) communication module or a power line communication (PLC) module).A corresponding one of these communication modules may communicate withthe external electronic device via the first network 798 (e.g., ashort-range communication network, such as Bluetooth®, wireless-fidelity(Wi-Fi) direct, and/or a standard of the Infrared Data Association(IrDA)) or the second network 799 (e.g., a long-range communicationnetwork, such as a cellular network, the Internet, and/or a computernetwork (e.g., LAN or wide area network (WAN)). Bluetooth® is aregistered trademark of Bluetooth SIG, Inc., Kirkland, Wash. Thesevarious types of communication modules may be implemented as a singlecomponent (e.g., a single IC), or may be implemented as multiplecomponents (e.g., multiple ICs) that are separate from each other. Thewireless communication module 792 may identify and authenticate theelectronic device 701 in a communication network, such as the firstnetwork 798 or the second network 799, using subscriber information(e.g., international mobile subscriber identity (IMSI)) stored in thesubscriber identification module 796.

The antenna module 797 may transmit and/or receive a signal and/or powerto and/or from the outside (e.g., the external electronic device) of theelectronic device 701. According to one embodiment, the antenna module797 may include one or more antennas, and, therefrom, at least oneantenna appropriate for a communication scheme used in the communicationnetwork, such as the first network 798 and/or the second network 799,may be selected, for example, by the communication module 790 (e.g., thewireless communication module 792). The signal and/or the power may thenbe transmitted and/or received between the communication module 790 andthe external electronic device via the selected at least one antenna.

At least some of the above-described components may be mutually coupledand communicate signals (e.g., commands and/or data) therebetween via aninter-peripheral communication scheme (e.g., a bus, a general purposeinput and output (GPIO), a serial peripheral interface (SPI), and/or amobile industry processor interface (MIPI)).

According to one embodiment, commands and/or data may be transmittedand/or received between the electronic device 701 and the externalelectronic device 704 via the server 708 coupled with the second network799. Each of the electronic devices 702 and 704 may be a device of asame type as, or a different type from, the electronic device 701. Allor some of operations to be executed at or by the electronic device 701may be executed at one or more of the external electronic devices 702,704, or 708. For example, if the electronic device 701 should perform afunction and/or a service automatically, or in response to a requestfrom a user or another device, the electronic device 701, instead of, orin addition to, executing the function and/or the service, may requestthe one or more external electronic devices to perform at least a partof the function and/or the service. The one or more external electronicdevices receiving the request may perform the at least a part of thefunction and/or the service requested, and/or an additional functionand/or an additional service related to the request, and transfer anoutcome of the performing to the electronic device 701. The electronicdevice 701 may provide the outcome, with or without further processingof the outcome, as at least a part of a reply to the request. To thatend, a cloud computing, distributed computing, and/or client-servercomputing technology may be used, for example.

One embodiment may be implemented as software (e.g., the program 740)including one or more instructions that are stored in a storage medium(e.g., internal memory 736 or external memory 738) that is readable by amachine (e.g., the electronic device 701). For example, a processor ofthe electronic device 701 may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. Thus, a machine may be operated to perform at least onefunction according to the at least one instruction invoked. The one ormore instructions may include code generated by a compiler or codeexecutable by an interpreter. A machine-readable storage medium may beprovided in the form of a non-transitory storage medium. The term“non-transitory” indicates that the storage medium is a tangible device,and does not include a signal (e.g., an electromagnetic wave), but thisterm does not differentiate between where data is semi-permanentlystored in the storage medium and where the data is temporarily stored inthe storage medium.

According to one embodiment, a method of the disclosure may be includedand provided in a computer program product. The computer program productmay be traded as a product between a seller and a buyer. The computerprogram product may be distributed in the form of a machine-readablestorage medium (e.g., a compact disc read only memory (CD-ROM)), or bedistributed (e.g., downloaded or uploaded) online via an applicationstore (e.g., Play Store™), or between two user devices (e.g., smartphones) directly. If distributed online, at least part of the computerprogram product may be temporarily generated or at least temporarilystored in the machine-readable storage medium, such as memory of themanufacturer's server, a server of the application store, or a relayserver.

Herein, embodiments of the present disclosure are described in detailwith reference to the accompanying drawings. It should be noted thatsame or similar elements may be designated by the same referencenumerals/letters even though they are shown in different drawings. Inthe description herein, specific details such as detailed configurationsand components are provided to assist with the overall understanding ofthe embodiments of the present disclosure. Various changes andmodifications of the embodiments described herein may be made withoutdeparting from the scope of the present disclosure. Certain detaileddescriptions may be omitted for clarity and conciseness.

The present disclosure provides for various modifications and variousembodiments. It should be understood that the present disclosure is notlimited to the various embodiments explicitly described or detailedherein, and that the present disclosure includes modifications,equivalents, and alternatives within the scope of the presentdisclosure.

Although terms including an ordinal number such as first, second, etc.,may be used for describing various elements, the elements are notrestricted by such terms. Such terms are used to distinguish one elementfrom another element, and do not imply any specific ordering. As usedherein, the term “and/or” includes any and all combinations of one ormore associated items. Singular forms are intended to include pluralforms unless the context clearly indicates otherwise. In the presentdisclosure, it should be understood that the terms “include” or “have”indicate the existence of a feature, a number, a step, an operation, astructural element, a part, or a combination thereof, and do not excludethe existence or probability of the addition of one or more otherfeatures, numbers, steps, operations, structural elements, parts, orcombinations thereof.

According to one embodiment, at least one component (e.g., a manager, aset of processor-executable instructions, a program, or a module) of theabove-described components may include a single entity or multipleentities. One or more of the above-described components may be omitted,or one or more other components may be added. Alternatively oradditionally, a plurality of components (e.g., a manager, a set ofprocessor-executable instructions, a program, or a module) may beintegrated into a single component. In this case, the integratedcomponent may still perform one or more functions of each of theplurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. Operations performed by the manager, the set ofprocessor-executable instructions, the program, the module, or anothercomponent may be carried out sequentially, in parallel, repeatedly, orheuristically, or one or more of the operations may be executed in adifferent order or omitted, or one or more other operations may beadded.

What is claimed is:
 1. A method of implementing a hybrid automaticrepeat request (HARQ) process, comprising: transmitting, by atransmitter to a receiver, an initial transmission of the HARQ process;receiving, by the transmitter from the receiver, receiver decodingcapability information; setting, by the transmitter, a retransmissionduration based on the receiver decoding capability information; andimplementing, by the transmitter, a retransmission of the HARQ processbased on the retransmission duration.
 2. The method of claim 1, wherein:the retransmission of the HARQ process is a first retransmission of theHARQ process, and implementing the first retransmission of the HARQprocess based on the retransmission duration comprises: determining, bythe transmitter, that no acknowledgement (ACK) has been received by anend of the retransmission duration; and implementing, by the transmitterresponsive to the determination that no ACK has been received by an endof the retransmission duration, a second retransmission of the HARQprocess or a timeout process.
 3. The method of claim 1, wherein settingthe retransmission duration based on the receiver decoding capabilityinformation comprises setting a modulation order of the retransmissionof the HARQ process based on the receiver decoding capabilityinformation.
 4. The method of claim 1, wherein setting theretransmission duration based on the receiver decoding capabilityinformation comprises setting a number of data subcarriers for theretransmission based on the receiver decoding capability information. 5.The method of claim 4, wherein setting the number of data subcarriersfor the retransmission comprises aggregating multiple users in at leastone multi-user physical-layer-convergence-procedure protocol data unit(MU-PPDU) and allocating an appropriate resource unit (RU) size for eachof the multiple users.
 6. The method of claim 4, wherein setting thenumber of data subcarriers for the retransmission comprises allocatingan appropriate bandwidth (BW) for the retransmission.
 7. The method ofclaim 1, wherein setting the retransmission duration based on thereceiver decoding capability information comprises setting a number ofbits of the retransmission of the HARQ process based on the receiverdecoding capability information.
 8. The method of claim 7, whereinsetting the number of bits of the retransmission of the HARQ processcomprises setting a number of parity bits or information bits includedin the retransmission.
 9. The method of claim 7, wherein setting thenumber of bits of the retransmission of the HARQ process comprisesincluded padding in the retransmission.
 10. The method of claim 1,wherein setting the retransmission duration comprises using at least oneparameter value that deviates from at least one default parameter valuefor the retransmission of the HARQ process such that the retransmissionduration increases.
 11. A method of implementing a hybrid automaticrepeat request (HARQ) process, comprising: receiving, by a receiver froma transmitter, an initial transmission of the HARQ process;transmitting, by the receiver to the transmitter, receiver decodingcapability information; receiving, by the receiver from the transmitter,a retransmission; and implementing, by the receiver, a decoding andfeedback process for the retransmission.
 12. The method of claim 11,wherein the receiver transmits the receiver decoding capabilityinformation as at least a part of a control frame.
 13. The method ofclaim 11, wherein the receiver transmits the receiver decodingcapability information as at least a part of a feedback frame.
 14. Themethod of claim 11, wherein the receiver transmits the receiver decodingcapability information as at least a part of a connection establishingprocess.
 15. The method of claim 11, wherein the receiver the decodingcapability information indicates a throughput of the receiver.
 16. Amethod of implementing a hybrid automatic repeat request (HARQ) process,comprising: receiving, by a transmitter from a receiver, receiverdecoding capability information; receiving, by the transmitter from thereceiver, feedback regarding a transmission of the HARQ process;determining, by the transmitter, to implement a retransmission based onthe feedback; determining, by the transmitter, a decoding time based onthe receiver decoding capability information and based on a size of theretransmission; determining, by the transmitter based on the decodingtime, to implement a remediation process; and implementing, by thetransmitter, the remediation process.
 17. The method of claim 16,wherein the remediation process comprises setting a retransmissionfeedback timeout duration based on the receiver decoding capabilityinformation.
 18. The method of claim 17, wherein the retransmissionfeedback timeout duration is at least equal to a sum of (i) a durationof the retransmission and (ii) an additional time, and the additionaltime is set by the transmitter based on the receiver decoding capabilityinformation.
 19. The method of claim 16, wherein determining, by thetransmitter based on the decoding time, to implement a remediationprocess comprises: estimating, based on the decoding time, a time atwhich retransmission feedback should be received; and determining thatan estimated retransmission feedback timeout period does not encompassthe time at which the retransmission feedback should be received. 20.The method of claim 16, wherein the remediation process comprisespulling, by the transmitter, the feedback according to a deferredfeedback scheme.